DEGASSING OF GAS-ATOMIZED AL-LI BASE ALLOY POWDERS .1. MASS-SPECTROMETRY STUDIES

The degassing characteristics of AI-Li base alloy powders with differe nt Li concentrations were studied using quadrupole mass spectrometry. In the presence of Li, H-2 evolution occurred under ultra high vacuum at T approximate to 200 degrees C and at T approximate to 500 degrees C. The hydrogen peak at T approximate to 200 degrees C was associated with the decomposition of LiH and was not observed in non-lithium cont aining Al alloys. Hydrogen evolution at T approximate to 200 degrees C was lower for powders that had experienced longer exposure to ambient atmosphere. Water evolution was detected at T approximate to 100 degr ees C and T approximate to 200 degrees C and decreased at T>250 degree s C with N-2 being evolved at T approximate to 460 degrees C. For lith ium containing alloys, CO was detected at T approximate to 260 degrees C due to the breakdown of carbon dioxide within the quadrupole analyz er.